About TLD5190QV minimum duty & Freq.

[rsiigod]

We need to design the AR-HUD backlight application.
Could you provide the minimum output dimming duty in digital PWM?
Minimum Frequency range?

[Kanahaiya_K]

Hi @rsiigod 

Thanks for posting on the Infineon Developer Community.

The device TLD5190QV will start in Buck mode and the mode of the device will be changed automatically by measuring the DC-DC duty cycles of the low-side gate drivers LSGD1 and LSGD2. The minimum Duty cycle in both modes are mentioned below

For increasing output voltage:

    Buck-boost to boost  = 27% 

 For decreasing output voltage:

   Boost to buck-boost = 11% 

For more details, you can refer to the datasheet of the TLD5190QV.

The device will support the minimum frequency range of 200kHz.

You can refer to this Design tools for the calculation of external components and the  other parameters.

Best Regards
Kanahaiya

[rsiigod]

@Kanahaiya_K 

Good day~
Sorry, I'm modifying my question, because I misunderstood what my colleague wanted to ask....

Could you provied the the minmun dimming duty in digital PWM(PWMI PIN)? Frequency range ?

[Kanahaiya_K]

Hi @rsiigod 

It is analyzed that there is no such restriction for minimum duty cycle and frequency limit for PWMI pin.
The light can be regulated even at a lower frequency(say 10 Hz) and duty cycle lower than 1% but the stroboscopic effect will come into the picture.
When we are operating at the lower frequency and duty cycle then obviously the voltage and current will be heavily affected at the output stage. So, you can choose the frequency and duty cycle based on your application.

Best Regards
Kanahaiya

[rsiigod]

@Kumarkanahai 
Good day~

@Brianwu is my colleague, now he has joined the forum and needs your help to solve the problem.

Best Regards
Ade

[Brianwu]

Hi IFX

Thanks your feedback.

1. How is PWMI pin operation range of frequency? 

2. 

[Brianwu]

Hi IFX

Please check if  PWMi  frequency use  200Hz, PWM duty cycle 0.2%, TLD5190QV digital dimming is okay ? 

Thanks

[Kanahaiya_K]

Hi @Brianwu 

As I mentioned above, The device can be used even at a lower frequency i.e. 10 Hz, and duty cycle less than 1%. But, The flickering (stroboscopic effect ) will come into the picture at frequencies lower than 100 Hz.

The Nominal frequency Range of the operation at the PWMI Pin is 100-500Hz.

For more details ,you can refer to the attached documents.

So, You can use the device at 200 Hz. Can you please let me know the reason behind using 0.2% Dimming duty cycle?

Best Regards
Kanahaiya.

[Brianwu]

Hi 

This application on ARHUD Backlight, in order to need to get contrast 1:500 that need use 0.2% duty /200Hz?

Could you help to check and response? thnaks   

[Brianwu]

 Hi 

Could you help to replay ?

Thanks 

[Kanahaiya_K]

Hi @Brianwu 

The regulation is affected by load type, and compensation network. Regulation on buck boost current mode controllers with compensation is difficult to achieve below 3%. An additional PWM p-mos is helping to achieve sharper waveforms but in any case, 0.2% is not achievable and it is not recommended 

Regards,
Kanahaiya

[Brianwu]

Hi Kanahaiya

Thanks, Could you also check the minimun duty  with 200Hz is recommend use ? 

[Kanahaiya_K · Accepted solution]

Hi @Brianwu 

As it is mentioned above, the minimum duty cycle at any frequency is 3 %.

Regards,
Kanahaiya